Research On Active Disturbance Rejection Controller For Vibrating Displacement Of Continuous Casting Mold Driven By Servo Motor

Continuous casting is important to product the iron and steel,and the mold is recognized as one of the key device which makes the casting blank forming in continuous casting.The vibration device for continuous casting mold driven by servo motor has a significant effect on improving the quality of the casting blank,improving production efficiency and saving energy.However,there are some problems in the vibration system,such as the nonlinear periodic function(its inverse solution is no unique)between the rotation angle of motor with the vibration displacement of mold,coaxial error between the motor and the reducer,friction nonlinearity and the time-varying load torque disturbance of motor,which make the tracking accuracy of the waveform worse.Therefore,to ensure the vibration device accurately and quickly tracking the desired vibration waveform,the analysis and the experimental research of auto disturbance rejection control of the mold's vibration displacement are studied in this paper.First of all,the whole structure and working principle of the vibration displacement system for continuous casting mold driven by servo motor is introduced in this paper,and the whole model of the system is given.This paper analyzes the nonlinear periodic function(its inverse solution is no unique,which is not conducive to tracking control)between the rotation angle of motor with the vibration displacement of mold,then a nonlinear algorithm is presented to ensure the mapping relation between motor rotation angle and mold displacement and researched by simulation,which lay the foundation for tracking control.Secondly,the model of system is discretized,and a three order extended state observer is designed to observe coaxial error,friction nonlinearity and the time-varying load disturbance.After that,the nonlinear error feedback controller is designed to suppress the tracking error and compensate the external disturbance.Simulation results show the effectiveness of the designed controller.Then,an auto disturbance rejection controller based on parameter self-tuning is presented to ensure the accuracy and robustness on different waveforms tracked by the mold,and the offline tuning control law parameters are calculated by the multi-objective optimization algorithm.The simulation results show that the designed controller has high tracking precision and smooth switching.Finally,using the existing high-speed programmable control module FM458,the PI control,the auto disturbance rejection control,and the control program of the parameter self-tuning control algorithm for the vibration displacement tracking system of the continuous casting mold driven by the servo motor are developed.The experimental data and the tracking curves shown in the PC monitoring system show the effectiveness of the proposed control algorithm.The auto disturbance rejection control with parameter self-tuning has higher tracking control precision.